Bitcoin Forum

When using X1 to X16 PCIE, and X16 extension risers do I just hook them up?  Or do I have to splice some wires?



And if I were to use 2 separate PSUs, one to power the system and 3 7970s and the other PSU to power the other 2 7970s, do I have to splice anything there?


I have been doing a ton of research and I read somewhere that to use the the X1 to X16 riser cables/cards you have to splice some wire.

And on the PSUs I read that you have to short one of the ATX connectors wires?


Can anyone confirm this?


Any info is greatly appreciated.



Thanks

Can't help with with PCI-e...

for the PSU yes... You either have to get a 24pin y cable (http://www.frozencpu.com/products/5637/), or perform a manual wiring method (shorting a cable sounds right) like they did here with a paperclip: http://aphnetworks.com/lounge/turn_on_psu_without_motherboard_the_paperclip_trick.

For PCIE it all depends on how many you are using and on what cards. If you are using 3+ PCIE risers on power hungry cards, then you will need to splice cables to allow for molex connection (or buy pre-spliced 'powered' molex connectors). If you are planning on needing 2 PSUs, then I would imagine that you will probably need powered risers.

Thanks for the replies.



I was planning on using 5 7970s.

The motherboard I have in mind has 2 X16 PCIEs and 3 X1 PCIes.  So I was going to use 2 X16 extensions and 3 X1 to X16 adapters.

I will look up and see if I can find any powered riser cards.  I have been having trouble finding any that don't ship from china really.


Its really hard to gauge how much power these cards will use when mining.  I have read everything from one guy having 5 running on a 1200W gold PSU.  Then I read another guy saying they use almost 400W while mining.  Which would be 2000W just for the cards alone with no overhead.

When I get home I will do some more research.  Thanks again.

You do not need to splice any PCIe extender cables.  Ever.  Under no circumstances.
If you were to plug your GPU directly onto the motherboard, is there any place for an added molex power connector?  No.
If you are only extending the PCIe connectors with extender cables, then you never need to cut, splice or add any molex non since.
Never.

The paperclip trick for the PSU works great.  That's what I do, even in my little youtube video.
And yes I use uncut PCI extenders too.

You do realize that the PCIE slots themselves deliver up 75W of power to GPUs through the mobo, yes? Hence the reason for a molex bypass (I'm not sure but I do not believe that the 1x->16x is capable of delivering 75W).

So you are only talking about the X16 extensions right?

The X1 to X16 adapters are different and need power spliced in?


If it does indeed need power spliced in can anyone point me towards a guide or instructions or something.

This is false. 5970's require 75w through the PCIe slots. 1x can't deliver that. You need molex to provide the required power.

You can find pci-e pins layout here:
http://en.wikipedia.org/wiki/PCI_Express (http://en.wikipedia.org/wiki/PCI_Express)

The diagram shows that power is delivered only on pins common to all lanes and doesn't differ for x1 nor x16.
The wiki says also that only graphics card is allowed to draw 75W and any other card can draw much less (10W or 25W). I believe this is not due to port limitation but rather to thermal design of the whole computer system. And maybe also due to power density (interferences?!).

I run 3x7970Ghz @640khash/s each (stock clocks) on opensuse linux distro.
one x16 and two x1 standard 19cm risers.

Even if PCIE can delivery the power, here's another reason to go with powered risers

https://bitcointalk.org/index.php?topic=161242.0

and here

https://bitcointalk.org/index.php?topic=102890.0

I use x16 extensions and x1 extensions and I do not need to add power to anything.  Not even 5970s which have dual GPUs.

However a 5970 will not run on an x1 PCI.  Maybe it wants more power, or maybe an x1 cannot support a dual GPU on an X1.
Power comes from the proper PSU with the proper amps and plugs.  (Non of those Molex to PCI plugs!)  (I am unloading those worthless things on ebay.  SATA to PCI adapters are also worthless.)